The World's Most Poisonous Plants

Poison ivy, cactuses, and stinging nettles are the most dangerous plants most Americans encounter. However, there is a whole range of potentially lethal flora that makes the side effects of these plants seem negligible by comparison. Simply touching a number of these plants is enough to kill or disfigure a person, all in very painful, unpleasant ways. While you’ll have to venture to far-away lands to encounter some of these plants, others are growing right in your backyard.

 

 

You’ll find the words “castor oil” on a number of candy bar wrappers, but this ingredient in the sugary goodness you’re consuming comes from a very deadly source: the castor oil plant. Castor oil plant seeds (often referred to as castor “beans”) carry a compound called ricinolein, the basis for the poison Ricin. To put the potency of Ricin in context, the US military considered using it as a chemical weapon during WWI, and a Bulgarian dissident (Georgi Markov) was murdered with a Ricin-tipped umbrella in London in 1978. The castor oil plant seeds carry ricinolein in small quantities, but eating just a handful of them is enough to kill a full-grown adult.  

 

People with ricinolein in their systems can expect to die within 3-5 days of exposure, and like many other plant toxins, it’s not a pretty way to go. The toxin causes extensive internal bleeding combined with diarrhea and vomiting. This leads to severe dehydration and eventually organ failure, at which point the game is up. 

 

 

The Manchineel tree is an especially nasty backyard threat. Native to tropical areas (look out, Floridians), any sort of contact with this tree is potentially lethal. Cutting it down releases a fine spray of poison and burning the trees creates a deadly cloud of smoke. These trees are best left entirely alone; even contact with water running off of the trees in a rainstorm is enough to make your skin blister. 

 

The blistering, by the way, can be horrific. One physician conducted an autopsy on an individual who had ingested the sap of the Manchineel tree and likened the victim’s GI tract to the insides of someone who had “consumed a can of lye.” Frequent exposure to small amounts of the toxin can also prove lethal as it deteriorates your liver and kidneys. Caribbean natives used to put the poisonous sap on their arrow tips, and allegedly even tied prisoners to these trees as a form of torture. 

 

 

The Gympie Gympie, a shrub native to Indonesia and Australia, has good reason to be feared. While it won’t always kill its victim, the pain associated with this stinging plant is unparalleled. One WWII soldier was strapped to a hospital bed for three weeks after a sting so that he wouldn’t harm himself. Another soldier during the same period allegedly shot himself after using a Gympie Gympie leaf as toilet paper on a training exercise.  

 

The leaves and twigs of the Gympie Gympie have sharp, fine hairs that penetrate the skin and then deliver a neurotoxin. The stinging sensation is reported to have lasted for months in some victims, and there are also cases of people going into anaphylactic shock after coming in contact with the plant. While the toxin isn’t typically enough to kill a person on its own, the pain drives many victims to suicide. 

 

 

Giant hogweed is an invasive species of plant that comes equipped with its own little shop of horrors. The word to remember if you ever encounter these enormous weeds is “phototoxicity.” Phototoxicity is the reaction that a toxin has on a victim when it is exposed to sunlight. Hogweed is like poison ivy on steroids: it turns exposed skin into an itchy, irritating blister, and will also cause eye irritation and potentially permanent blindness. This isn’t a short-lived affair, either. The scars giant hogweed leaves victims with are typically purple or brown and can last for a number of years. Be mindful of these nasty plants, as they’ve begun to spread across North America. 

 

 

Jimson Weed, part of the nightshade family, is as deadly as its cousin, deadly nightshade.  Jimson Weed can be lethal to both humans and animals when ingested, with symptoms that range from elevated heart rates to overheating.  The most interesting and potentially terrifying aspect of Jimson Weed is its ability to erase the line between fiction and reality in the human mind. On top of this toxically-induced delirium, these episodes are often followed by periods of amnesia and a painful sensitivity to light. Though Jimson Weed doesn’t always kill its victims, it can induce hellish psychological trips and often produce episodes of uncontrolled physical violence.